double log1p(double x) {
    if (x == 0.0)
        return 0.0;
    if (x == -1.0)
        return double.negativeInfinity;
    if (x < -1.0)
        return double.nan;
    double xAbs = x.abs();
    if (xAbs < 0.5 * 4.94065645841247e-324)
        return x;
    if ((x > 0.0 && x < 1e-8) || (x > -1e-9 && x < 0.0))
        return x * (1.0 - x * 0.5);
    if (xAbs < 0.375) {
        List<double> coeffs = [
             0.10378693562743769800686267719098e+1,
            -0.13364301504908918098766041553133e+0,
             0.19408249135520563357926199374750e-1,
            -0.30107551127535777690376537776592e-2,
             0.48694614797154850090456366509137e-3,
            -0.81054881893175356066809943008622e-4,
             0.13778847799559524782938251496059e-4,
            -0.23802210894358970251369992914935e-5,
             0.41640416213865183476391859901989e-6,
            -0.73595828378075994984266837031998e-7,
             0.13117611876241674949152294345011e-7,
            -0.23546709317742425136696092330175e-8,
             0.42522773276034997775638052962567e-9,
            -0.77190894134840796826108107493300e-10,
             0.14075746481359069909215356472191e-10,
            -0.25769072058024680627537078627584e-11,
             0.47342406666294421849154395005938e-12,
            -0.87249012674742641745301263292675e-13,
             0.16124614902740551465739833119115e-13,
            -0.29875652015665773006710792416815e-14,
             0.55480701209082887983041321697279e-15,
            -0.10324619158271569595141333961932e-15];
        return x * (1.0 - x * chebyshevBroucke(x / 0.375, coeffs));
    }
    return log(1.0 + x);
}
double chebyshevBroucke(double x, List<double> coeffs) {
    double b0, b1, b2, x2;
    b2 = b1 = b0 = 0.0;
    x2 = x * 2;
    for (int i = coeffs.length - 1; i >= 0; --i) {
        b2 = b1;
        b1 = b0;
        b0 = x2 * b1 - b2 + coeffs[i];
    }
    return (b0 - b2) * 0.5;
}
